ES2334621B1 - PROCEDURE FOR OBTAINING FUELS DERIVED FROM URBAN SOLID WASTE. - Google Patents

Abstract

Procedure for obtaining fuels urban solid waste derivatives.

A new suitable fuel has been developed for use in industrial facilities with high furnaces temperature. It is a fuel in two possible formats. TO Bulk or compacted this product is obtained from waste urban solids through a certain procedure.

The purpose of the process is to maximize the calorific value of the material, so that its employment in thermal power plants or in industrial facilities, usually powered by fossil fuels. For this they will use certain reagents whose use for this application is novel. Through the use of this fuel is achieved, among other advantages, eliminate solid urban waste, prolong the life span from landfills, substitute fossil fuels for alternatives, reduce CO2 emissions and achieve European objectives of waste recovery. By its composition it will be seen that it can be used in facilities that guarantee the minimum temperature necessary to prevent the formation of certain compounds not desired, among which are the cement plants, factories of ceramic materials, thermal power plants and others.

Description

Procedure for obtaining fuels urban solid waste derivatives.

Technical sector

1.- Preparation of Alternative Fuels

2.- Waste Treatment

State of the art

There are currently various procedures for the treatment of urban solid waste, hereinafter RSU. Be it will start in all cases of the budget that there is a orderly collection of this waste, regardless of whether collect different fractions selectively for recycling or on the contrary, the entire MSW is collected together, or from which Be your destiny.

Among the treatment alternatives in use Currently the following are worth mentioning: Controlled landfill (the deposition of MSW in uncontrolled landfills is prohibited currently), incineration plants with or without recovery of energy, with complementary contribution of natural gas or without it, plants of composting of the organic fraction of the waste, plants of manual or automated triage or classification of MSW, collected selectively or in bulk, biomethanization plants, plants gasification, pyrolysis, aerobic fermentation plants for waste stabilization and subsequent energy use or combinations of the above. It should be mentioned that the deposition of RSU in controlled landfill is no longer a valid option, since Directive 2006/12 / EC does not consider discharge as an alternative to treatment.

The alternative presented could be consider an aerobic waste fermentation technique or a Biological mechanical treatment (TMB or TBM), with a series of particularities that make it original and different from how much you can find now, and clearly advantageous as you can I will check. There are treatments mechanical-biological that are currently in use in countries such as Italy or Germany, as described in the document ES 2 133 612 T3, which they get in greater or lesser measure stabilize the residue and even make it useful as fuel, usually with heat supply for drying. In In this case, no heat is supplied by using hot gas, but a technique is used absolutely different so that the waste itself generates quickly and effective heat needed for stabilization, drying and consequent validation as industrial fuel, suitable for electrical generation or thermal energy for processes.

Summary Explanation of the Invention

A new suitable fuel has been developed for use in industrial facilities with high furnaces temperature. It is a fuel in two possible formats: A bulk or compacted. This product is obtained from waste urban solids through a procedure that will be explained to continuation with detail.

The main object of the process consists of maximize the calorific value of the material, so that it is interesting its use in thermal power plants of production of electricity or in industrial facilities, usually fueled by fossil fuels. For this they will be used certain reagents whose use for this application is totally new.

By using this fuel it is achieved, among other advantages, eliminate urban solid waste, prolong the life of landfills, replace fossil fuels by alternative, reduce total emissions of CO_ {2} and achieve the European valuation objectives of waste. By its composition it will be seen that this fuel can be used in facilities that guarantee the minimum temperature necessary to prevent the formation of certain compounds not desired, among which are the cement plants, factories of ceramic materials, thermal power plants and others.

Description

The fuel object of this investigation can be obtained from the fraction "rest" of the urban solid waste, hereinafter RSU, or from called "rejection" of treatment plants for this waste. When referring to the fraction "rest" we refer to the part of the MSW that is not subject to selective collection for reuse or recycling. It's about what is commonly called "garbage", and consists of those organic remains biodegradable, non-biodegradable and inorganic organic that does not they can be recycled or, even though they can be recycled, they cannot They have been selectively collected for this purpose.

Normally this fraction "rest" has as destination the municipal landfills or plants of incineration, biomethanization or composting, as well as plants in which two or more of the previous technologies are combined. Plus recently new technologies have appeared such as pyrolysis or gasification You could say that of the previous technologies there are some that can be considered finalists, that is, they constitute an end point to the path traveled by the residue, and others that involve intermediate stages within a chain of treatment. It is assumed that there is a waste collection municipal, separated or not by fractions. They are technologies finalists dumping in controlled landfills and incineration, as well as pyrolysis and gasification. The first of these options are restricted by current European regulations, which prevents the dumping of municipal waste that has not been subject to of pretreatment The others assume, usually although not Always, an energy recovery. This energy turns out to be always very inferior to the internal energy contained in the matter that makes up the residue. This is due to the losses that occur  when thermal energy becomes electrical in plants incinerators or losses of various types in the other mentioned technologies. The method presented here does not imply conversion into electrical energy and does not imply important losses of thermal type, because the fuel obtained will be burned in its final destination without previous conversions, maximizing this mode the amount of energy that can be recovered. Is convenient to keep in mind that within the RSU they predominate materials such as plastics, cellulose or textiles with an important calorific value The method that is exposed will raise this calorific value, so that the amount of fossil fuel replaced as large as possible.

The possibility of carrying out this process from the so-called "rejection" of the plants of waste treatment It is usual for MSW, after being collected, transported to treatment plants "no finalist ", that is, where certain fractions are obtained that can be used for different purposes while remaining others that lack utility, so it still requires a "queued" finalist treatment. Among these plants are find the manual, automatic or mixed classification of waste, composting, biomethanization and others. In these mainly metals, paper / cardboard, plastics and organic matter, which is sometimes even collected separately and that is recovered in the form of compost or by obtaining biogas with which it can then occur electric power or it can be used for thermal uses Industrial or domiciliary. There is always a part nothing negligible of the admitted waste that, after all these processes, could not be classified, composted, gasified or recovered in any way. This fraction is called "rejection" and may be subject to the treatment here exposes.

In the case that is exposed, first the waste to be treated is received in a covered ship, in order to avoid the incidence of rainfall of the same type atmospheric. It is preferable that the time elapsed in this Reception area does not extend beyond one week. TO then the material is crushed to an average size of particle around 150 mm (stage 1), although a granulometric range up to 250 mm approximately. At the exit of crushing is passed to the material under an electromagnet, of way that ferrous metals are removed, which do not provide power calorific, which could steal energy from a thermal process later and they are also recyclable in other ways. Is It is also possible to pass the material through a separator induction currents, also called Foucault, to eliminate non-ferrous metals, such as aluminum, copper and others. This last separation should be carried out in case a important presence of these metals in the initial material, and It will be especially relevant if working with mass-collected MSW and not previously treated. If the initial material with which work is the rejection of treatment of a plant in which they separate non-ferrous metals, hopefully their presence in the final result does not exceed 0.1%.

After this stage an accumulation would be achieved of material of the mentioned caliber that has a certain moisture content, around 25-30% although This varies greatly depending on the treated waste. There will also be a  percentage of biodegradable organic matter. The humidity depends on large extent of the origin of the residue. If it's waste gross, directly contributed by the municipal collection, the moisture content is higher than if it is the fraction "rejection" of a treatment plant where recovered a majority of putrescible organic matter. It is convenient to indicate that none of the treatments "do not finalists "carried out with waste has an efficiency 100%, so treatment rejection always has a certain content in those fractions that have been wanted to extract for recovery, such as metals, cardboard, plastics or organic material.

To this accumulation of material two are added additives (stage 2) that constitute one of the main novelties of this process: It is an algae to accelerate the processes of fermentation and an aqueous based deodorizer. The first of they, as stated, is a microscopic algae, looking powdery and very fine texture, pale color and dry touch that, when be added to the crushed residue, accelerates the beginning of the fermentation reaction (step 3). After only 24 hours from the first crushing mentioned, even starting from a material with less than 20% organic matter, are obtained temperatures close to 50ºC, which arrive in days after exceed 70 ° C. The material accumulates in the form of a plateau and is flips daily, so that after each of the flips the temperature drops dramatically and increases again by the mentioned catalyst action. Every time the material is turned a large amount of steam is released. In this way, the moisture initially contained in the residue is evaporated by the heat generated by the material itself accelerated by the referred additive while lower calorific value, seriously affected by moisture, ascends progressively. He Second of the additives cited is a deodorizer. It's about a water-based odor eliminator that mixes with water in approximate ratio of 1-20 and sprinkle on the material, for example with a sulfatador. This implies the same time a contribution of water to the material, but in irrelevant quantity. The deodorizer can be applied more than once during the process If so it seems convenient. In principle, it has been considered convenient to use at least after each crushing of the material and prior to delivery of the finished product.

After a period of five to seven days in plateau with daily flipping, a large part of the humidity that initially contained the material has evaporated. Still interested reduce this humidity further, with a view to increasing its calorific value lower. This will proceed to the second crushing of the material, up to a grain size of 20-30 mm. Fractions that do not add value will also be eliminated Energetic to the result. This is going to be done the way it is explain below.

At least two machines are needed for this: A first to eliminate the part that does not interest (stage 4) and a second to crush the interesting fraction (step 5). These machines can be a ballistic separator or a vibrating screen in first and a crusher-granulator in second finished. The first (stage 4) will, on the one hand, eliminate particles smaller than a certain size through a mesh perforated with holes of the desired diameter, and on the other, within the part not screened, separate the grains called "rolling" and on the other the "planes". We call "rolling" to that part of the material that in a separator ballistic with inclined mesh tends to roll down the bottom of this slope, while the "plane" would be that material that does not roll downhill, so it tends to exit the ballistic separator at the top. This part flat is the one that interests to continue with the process, and is Composed mainly of plastics, cellulose both paper and cardboard as sanitary ware, textile fragments and other materials in least amount. Among the "rolling" we would find arid, rubbers or rubbers, certain textile fragments, such as footwear and a wide variety of rounded bodies. This fraction could be reprocessed in the first shredder, since an important part of it still has a power considerable calorific. In any case, it is normal to assume less than 10% by mass over the total material, so it could be dispensed with and eliminated any of the available means. Its separation is necessary so that stones, metals or other objects of great hardness do not enter in the second crusher, they could damage it. As it has been said, the ballistic separator also has perforated meshes to through which the land will be removed, part of the organic matter and some minor particles that contain the material. The purpose of removing this part is to remove all that which does not add energy value to the fuel.

This second crusher (stage 5) has the mission of reaching the final particle size that is going to interest for the final result. Your feed or flow of input would be the output of "planes" of the ballistic separator above, or the part not screened if it has simply been used a vibrating screen to separate particles of smaller caliber. He Outflow of this machine will consist of a set of particles of no more than 3 centimeters, indistinguishable appearance and considerable temperature, since this stage has been carried out while the fermentation of the material was taking place. TO effects of the biological process, crushing equals a flip similar to those made daily, so that the reaction of fermentation is briefly deactivated at this time to return to intensify then reaching temperatures again between 60 and 75 ° C.

With the material crushed for the second time, see it will form a plateau similar to the first one, which will also turn daily (stage 6). It must be kept covered in a ship ventilated, so that the moisture that the material gives off is evacuated through the ventilation system. In each of the flips you can see how the material gives off an important amount of steam, so that its humidity drops to As the days go by. Immediately after the second crushing (prior to stage 6) a power can be achieved lower calorific value of approximately 4,000 kcal / kg, or 16-17 Mj / kg. The humidity at this point can approach 15%. If allowed to stand on plateau with daily flip (stage 6), this calorific value amounts to values around 4,500 kcal / kg or 18-19 Mj / kg after about ten days, with a moisture content that drops to levels of 3% order. It could be said that they earn around 50 kcal / kg or 0.2 Mj / kg for each additional day of rest in this Second plateau for at least the first week. This progression It is not necessarily linear, but within a few days It could approach this way. This rapid gain of power calorific is mainly due to the use of the algae mentioned above, which accelerates fermentation (stages 3 and 6) so that moisture is detach as soon as possible, even with waste that at reception they have less than 20% biodegradable matter.

The main interest of abbreviating this period of moisture loss lies in reducing the surface need of treatment, and with it the total size of the plant fuel processing The necessary area for each of the two plateaus of material will be proportional to the time the material must pass in each phase, so reduce these residence times equals reducing the need for space and also the need to daily turn each of them, of so that it is not necessary to oversize the machines that leave to be used to carry out these flips.

After this second period of permanence in Plateau can be considered that the fuel is made. It is not it is strictly necessary to densify or compact it for transport, since the bulk product reaches a density of Approximately 450 kg / m3, so that you can carry a significant amount in any conventional transport, which you must necessarily keep the material protected from rainfall Under these conditions the product is suitable for use in industrial facilities that ensure, in accordance with the European regulations, a temperature of at least 800ºC during a time of at least 2 seconds. These requirements are met amply in several industries, such as those mentioned above. It only remains to spray it again with odor neutralizer, so that its subsequent handling be more bearable.

There is a variant to get and consume mode this fuel It's about the possibility of producing it in a way compacted, reaching a higher density and reducing surface requirements for the construction of the installation. In this case there will be a single crushing phase, in the that an intermediate size will be obtained between the previous two.

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In this variant we would use a shredder that produce granulometry fragments between 50 and 100 mm (stage 1). It will also be required in this case of a sieve to separate stones, earth and bodies without calorific value (stage 4 of the process above), as well as metal separation. These stages can be before or after crushing. If done so prior, the crusher will suffer less from the presence of materials unwanted, while if done later, the separation will be more effective, since the material will arrive more loose. In any case, the result of screening and crushing it will consist of an accumulation of material in fragments of 50-100 mm, in which cellulose will predominate, plastics and textiles, although there will be small amounts of Several other fractions. The seaweed will then be added referred to above to accelerate fermentation (stage 2), as well As the odor neutralizer. This result is accumulated intermediate in the form of a plateau (stage 3), turning daily for 5-7 days, just like it was done in the first variant After this time a plateau of material with a moisture content around the 15-20%, in fragments smaller than the first plateau from the previous case. Therefore, with the only variable of whether the aggregate separation is done before or after the first and only crushing, it can be said that the first four  Stages of this variant are common with the first case explained. The material will then be compacted (step 5) in a specific machine for this, process in which the material is heats and releases a lot of steam. With this process you They will achieve different objectives: On the one hand, decrease Drastic and immediate moisture. On the other, a significant increase in density, which allows to accumulate large quantities in smaller spaces Third, the resulting product becomes a consistent bar, which is not affected in any way by the wind, emits less odor than bulk material and, if wet by rain or other causes, moisture does not penetrate it, so that It only gets wet outside and can dry easily.

The diameter of the bars obtained by this procedure will depend on the machine used to produce them In principle it can be considered reasonable to work with diameters between 10 and 40 centimeters. Density in this format is greater than 1,000 kg / m 3, and its handling is simpler. You can proceed, for example, to storage in small cages on pallets, easily manipulated with wheelbarrows elevators The calorific value of this fuel is similar to previous. There is a notable difference between this fuel and the Previous, served in bulk: These bars cannot be entered directly in ovens for consumption. It is necessary to go through a crushing stage. To proceed to the furnace feed industrial is normally required that the size of the grains of fuel does not exceed 10 mm. This requires that there be an intermediary that transports the material in this format, making use of the advantage of its higher density than then crush it to the indicated size and serve it at final consumer, already crushed.

The choice of one or another format will look conditioned by the space available for drying, since the first variant consumes less energy but requires more surface, while the second, in which there is only one stage of drying in plateau, requires less total space, since the resulting bars can be easily stacked up to several meters high being able to accumulate large amount in very little surface, even outside ships.

Both formats correspond to a single fuel, which can take one form or another depending on the mentioned conditions. In general, with any of them, it will get a fuel with a calorific value of not less than 4,000 kcal / m 3 (16-17 Mj / kg), which means minus half the calorific value of fossil fuels usually used in industrial facilities such as Cemeteries or factories of ceramic materials for construction. Therefore, to replace a ton of traditional fuel not it would take more than, at most, two tons of this fuel alternative.

Finally, it should be noted that the fuel obtained in any of both formats can be mixed with various other compounds used as fuel in the aforementioned facilities, instead of being used in pure state. Among other substances, the remains of pruning should be noted  and gardening, crushed tires, flours crushed animals or wood waste.

Claims (5)

1. Method to obtain an alternative fuel for industrial purposes from urban solid waste, characterized by:

to)

Do not make use of additional energy contributions.

b)

Do use of algae as a catalyst for the biological reaction of fermentation.

C)

Remove the unusable fraction of the residue up to less than 20% by mass of the amount initial.

The stages of this method are:

one-

First crushing until 100-250 mm and metal removal.

2-

Application of additives for acceleration of fermentation and deodorization.

3-

Fermentation on plateau with flip Daily, one week.

4-

Screening in ballistic separator or similar for fraction removal without calorific value.

5-

Second crushing up 20-30 mm and possible addition of deodorizer

6-

Second fermentation on plateau, with I turn daily, one week.

2. Variant of the method defined in the first claim and therefore dependent on it to obtain an alternative fuel for industrial purposes from urban solid waste, characterized by:

to)

Do use of compaction to increase the density of material.

b)

Get through this compaction dramatically reduce the moisture of the residue, thus increasing its calorific value

The stages of this method are:

one-

First crushing until 50-100 mm and metal removal.

2-

Application of additives for acceleration of fermentation and deodorization.

3-

Fermentation on plateau with flip Daily, one week.

4-

Screening in ballistic separator or similar for fraction removal without calorific value. This stage It can also be carried out at the beginning of the process.

5-

Compaction by extrusion for raise the density of the material while eliminating the highest Part of the humidity.

3. Bulk alternative fuel for the industry characterized by:

to)

To have obtained from the rejection of a treatment plant for waste with separation of organic matter.

b)

To have been obtained by the process of claim first.

C)

Serve in bulk, with a density in around 450 kg / m 3.

d)

Possess a calorific value greater than 16 Mj / kg and a humidity below 15%.

4. Compacted alternative fuel for the industry characterized by:

to)

To have obtained from the rejection of a treatment plant for waste with separation of organic matter.

b)

To have been obtained by the procedure of the first claims and  second.

C)

Serve in compacted form, with a density greater than 1,000 kg / m 3.

d)

Possess a calorific value greater than 16 Mj / kg and a humidity below 15%.

5. Alternative fuel for industry characterized by containing at least one of the fuels of claims third and fourth, mixed with other possible alternative fuels for industrial facilities, such as crushed wood, crushed tires, flours of animal origin, waste or agricultural surpluses or dried WWTP sludge.